3dpcp/.svn/pristine/fd/fd3d907bff15ca64cf40d1164a7bfe340bb37dd5.svn-base
2012-09-16 14:33:11 +02:00

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/**
* @file
* @brief
*
* @author Thomas Escher
*/
#ifndef CACHE_DATA_ACCESS_H
#define CACHE_DATA_ACCESS_H
#include "slam6d/data_types.h"
#include <boost/interprocess/sync/interprocess_upgradable_mutex.hpp>
#include <boost/interprocess/sync/sharable_lock.hpp>
// hide the boost namespace and shorten others
namespace
{
namespace ip = boost::interprocess;
}
/**
* @brief Access object for data in a CacheObject.
*
* This object functions as a reading lock on the data in a CacheObject. While any of these objects exists with a lock on a CacheObject it is guaranteed the CacheManager won't remove it from memory when flushing the cache.
* It is derived from the DataPointer class, which already represents application-specific access operators for this data, and builds the locking functionality on top of it.
* A CacheDataAccess is returned by the accessing function in a CacheObject as a temporary and is constructed by these means (&&-ctor). Size and data pointer will be copied and the reading lock will also be obtained. When all CacheDataAccess instances for a given CacheObject are destroyed (fell out of scope) all read locks are gone and the CacheManager is able to remove its contained data from memory.
*/
class CacheDataAccess : public DataPointer {
class Lock : public PrivateImplementation {
public:
Lock(ip::interprocess_upgradable_mutex& mutex);
// on destruction, the lock has to be released, which comes from m_lock destruction
virtual ~Lock() {}
private:
ip::sharable_lock<ip::interprocess_upgradable_mutex> m_lock;
};
public:
// CacheDataAccess& operator=(const CacheDataAccess&) = delete;
// CacheDataAccess(const CacheDataAccess&) = delete;
//! Aquires a lock on the mutex and takes assigned data
CacheDataAccess(ip::interprocess_upgradable_mutex& mutex, unsigned int& size, unsigned char* data);
CacheDataAccess(CacheDataAccess&& other) : DataPointer(other) {}
//! Non-locking version
//CacheDataAccess(unsigned int& size, unsigned char* data);
//! Transfers the lock to this instance and also takes assigned data
//CacheDataAccess(const CacheDataAccess& other);
};
#endif //CACHE_DATA_ACCESS_H